Bottom Line:
We apply aerodynamic levitation to bulk rocks in preparation for microchemical analyses, and for evaporation and reduction experiments.The technique has great potential for the quantitative determination of evaporated materials from silicate melts.Reduction of oxides to metal is a means for the extraction and analysis of siderophile elements from silicates and can be used to better understand the origin of chondritic metal.

Background: In aerodynamic levitation, solids and liquids are floated in a vertical gas stream. In combination with CO2-laser heating, containerless melting at high temperature of oxides and silicates is possible. We apply aerodynamic levitation to bulk rocks in preparation for microchemical analyses, and for evaporation and reduction experiments.

Results: Liquid silicate droplets (~2 mm) were maintained stable in levitation using a nozzle with a 0.8 mm bore and an opening angle of 60°. The gas flow was ~250 ml min-1. Rock powders were melted and homogenized for microchemcial analyses. Laser melting produced chemically homogeneous glass spheres. Only highly (e.g. H2O) and moderately volatile components (Na, K) were partially lost. The composition of evaporated materials was determined by directly combining levitation and inductively coupled plasma mass spectrometry. It is shown that the evaporated material is composed of Na > K > Si. Levitation of metal oxide-rich material in a mixture of H2 and Ar resulted in the exsolution of liquid metal.

Conclusions: Levitation melting is a rapid technique or for the preparation of bulk rock powders for major, minor and trace element analysis. With exception of moderately volatile elements Na and K, bulk rock analyses can be performed with an uncertainty of ± 5% relative. The technique has great potential for the quantitative determination of evaporated materials from silicate melts. Reduction of oxides to metal is a means for the extraction and analysis of siderophile elements from silicates and can be used to better understand the origin of chondritic metal.

Figure 10: Sketch illustrating the set up for the evaporation experiment. The exhaust of the levitation chamber was connected to the inlet of the ICPMS. Argon was used as levitation gas.

Mentions:
Alkali (Na, K) evaporation experiments were conducted with a picritic basalt PB-63. The chemical composition of PB-63 was previously determined by X-ray fluorescence (XRF, Göttingen, Table 2). The liquidus temperature was 1620 °C. The picrite was pre-fused to a sphere in a graphite crucible before it was placed in the levitation nozzle. We used the closed sample chamber with Ar as levitation gas. The outlet of the levitation apparatus was directly connected to the source of an ICPMS in order to monitor the composition of the evaporated material (Fig. 10). The sample was heated and fused with variable laser energy. We monitored the stability of the sphere using the video system.

Figure 10: Sketch illustrating the set up for the evaporation experiment. The exhaust of the levitation chamber was connected to the inlet of the ICPMS. Argon was used as levitation gas.

Mentions:
Alkali (Na, K) evaporation experiments were conducted with a picritic basalt PB-63. The chemical composition of PB-63 was previously determined by X-ray fluorescence (XRF, Göttingen, Table 2). The liquidus temperature was 1620 °C. The picrite was pre-fused to a sphere in a graphite crucible before it was placed in the levitation nozzle. We used the closed sample chamber with Ar as levitation gas. The outlet of the levitation apparatus was directly connected to the source of an ICPMS in order to monitor the composition of the evaporated material (Fig. 10). The sample was heated and fused with variable laser energy. We monitored the stability of the sphere using the video system.

Bottom Line:
We apply aerodynamic levitation to bulk rocks in preparation for microchemical analyses, and for evaporation and reduction experiments.The technique has great potential for the quantitative determination of evaporated materials from silicate melts.Reduction of oxides to metal is a means for the extraction and analysis of siderophile elements from silicates and can be used to better understand the origin of chondritic metal.

Background: In aerodynamic levitation, solids and liquids are floated in a vertical gas stream. In combination with CO2-laser heating, containerless melting at high temperature of oxides and silicates is possible. We apply aerodynamic levitation to bulk rocks in preparation for microchemical analyses, and for evaporation and reduction experiments.

Results: Liquid silicate droplets (~2 mm) were maintained stable in levitation using a nozzle with a 0.8 mm bore and an opening angle of 60°. The gas flow was ~250 ml min-1. Rock powders were melted and homogenized for microchemcial analyses. Laser melting produced chemically homogeneous glass spheres. Only highly (e.g. H2O) and moderately volatile components (Na, K) were partially lost. The composition of evaporated materials was determined by directly combining levitation and inductively coupled plasma mass spectrometry. It is shown that the evaporated material is composed of Na > K > Si. Levitation of metal oxide-rich material in a mixture of H2 and Ar resulted in the exsolution of liquid metal.

Conclusions: Levitation melting is a rapid technique or for the preparation of bulk rock powders for major, minor and trace element analysis. With exception of moderately volatile elements Na and K, bulk rock analyses can be performed with an uncertainty of ± 5% relative. The technique has great potential for the quantitative determination of evaporated materials from silicate melts. Reduction of oxides to metal is a means for the extraction and analysis of siderophile elements from silicates and can be used to better understand the origin of chondritic metal.